The primary objective of the research proposal is to improve the measurement of effectiveness in the context of cost-effectiveness analysis. Patients' attitudes about health outcomes are often elicited inutility interviews with a trained research assistant. These face-to-face interviews, however, may not truly capture patients' attitudes due to subtle interviewer influences. Computer-based utility elicitation, on the other hand, may substantially improve the validity of the obtained utilities by removing interviewer influences and assuring identical treatment of all respondents. Further, computer-based elicitation over the Internet reduces the cost of assessment and may be just as valid as other formats. In this study, the validity of three utility elicitation formats will be compared: face-to-face interview elicitation, computer- based elicitation at Stanford, and computer-based elicitation over the Internet. For each format, validity will be measured in four ways using three utility instruments and two intermediate health states. Results will suggest which format is the best way to elicit utilities. Using the best possible measure of effectiveness can maximize the acceptability of cost- effectiveness rankings.